In recent years, hopes for high definition, large screen televisions such as-Hi Vision have been high and getting higher. In each of the fields of CRT, Liquid crystal displays, and Plasma Display Panels (hereafter referred to as PDP) progress has been made.
Of the above technologies, PDP in particular makes it possible to achieve a large screen with a small depth, and products in the 60-inch class have already been developed.
PDPs can be broadly divided into two types, Direct Current type (DC type) and Alternating Current type (AC type), but currently, the AC type, appropriate for increasingly large devices, is more common.
A typical AC panel discharge type PDP is constructed with a back glass panel and a front glass panel disposed opposite one another such that a space is formed between the panels. In order to form a gas discharge space, the periphery (not shown in the drawings) is sealed using a sealing material composed of a glass with a low melting point. Then, an inert gas (for example a mixture of He and Xe) at a pressure of substantially 300 Torr to 500 Torr (40-66.5 kPa) is enclosed in the space between the two plates.
Discharge electrodes are disposed in a stripe pattern on the front glass panel, and this arrangement is overlaid with a dielectric layer composed of a dielectric glass and a protective layer composed of Magnesium Oxide (MgO).
Address electrodes are disposed in a stripe pattern on the back glass panel, and a visible light reflective layer is provided so as to cover the address electrodes. On top of this arrangement, barrier ribs are disposed between the address electrodes to divide the space described above, and a phosphor layer composed of red, green or blue ultraviolet light excited phosphor is provided in the gaps between the barrier ribs.
Also, as disclosed in Japanese laid open patent application number 11-162358, a PDP having a plurality of hollow narrow tubes made of glass and arrayed on a substrate, red, green or blue phosphor layers applied to the inside surfaces of the tubes, and a discharge gas enclosed within the tubes has also proposed. In a PDP using hollow narrow tubes in this way there is no need to enclose the discharge gas between the two panels because the discharge gas is enclosed in the hollow narrow tubes, and manufacture of the PDP is therefore simplified. Also, since the hollow narrow tubes also serve as barrier ribs and the dielectric glass layer, the PDP may be lightened.
The PDP principle for light emission is basically the same as for fluorescent lighting: when an electric field is applied between electrodes and a glow discharge is generated in the discharge space, short wavelength ultra-violet light emitted from a discharge gas induces excited emission in the red, green and blue phosphors. However, in the case of a PDP, since the discharge energy to ultraviolet light conversion efficiency and the ultraviolet light to visible light conversion efficiency in the phosphor are low, it is difficult to achieve the high emission efficiency of fluorescent lighting.
There is, therefore, a desire for an improvement in the luminance and emission efficiency of a PDP.
Also, research aiming to provide a High Definition PDP's is in progress.
For example, research is also being carried out into the suppression of deterioration of the emission characteristics of the phosphor layers in a PDP.
Also, to provide a High Definition PDP, it is also important that the color temperature when white is displayed is raised by adjusting the color of each colored cell.